Apparatus for coating articles



Dec. 28, 1943. H. OSTERBERG APPARATUS FOR COATING ARTICLES Filed Dec. '4

, 1941 2 Sheets-Sheet 1 INVENTOR svfi v TTORNEY 1943. H. OSTERBERG 2,337,679

. APPARATUS FOR COATING ARTICLES Filed Dec. 4, '1941 2 Sheets-Sheet 2 ll/ll l W I N V E N T O R HAROLD 0573595526 material to be vaporized.

Patented Dec. 28, 1943 v I 2,337,679 APPARATUS roa COATING ARTICLES Harold Ostcrberg, Buflalo, N. Y., asslgnor to Spencer Lens Company, Buffalo, N. Y., a corporation of New York Application December 4, 1941, Serial No. 421,632

3 Claims. (Cl. 13-31) This invention. relates to the deposition of films from material vaporized in a vacuum and has particular reference to a new and improved apparatus for effecting the vaporization and deposition of the material in the vacuum.

An object of the invention is to provide a new and improved means for supporting the material to be vaporized.

Another object of the invention is to provide a new and improved means for evaporating the coating material. V

Another object of the invention is to-.provide a new and improved electrode having means for supporting the material to be vaporized and also having means for cooling said electrode during the use thereof.

Another object of the invention is to provide means for directing the vaporized material toward the siirface on which it is to be deposited and for preventing heat from reaching and said vaporized material reaching and adhering to the lower portion of the bell jar and other device forming the vacuum chamber.

Another object of the invention is to provide a new and improved crucible for supporting the Another object is to provide new and improved means for connecting said crucible with said electrode.

Another object is to provide new and improved shield means for preventing loss of heat from said crucible.

Another object of the invention is to provide a new means for evaporating a highly transparent material.

Other objects and advantages of the invention will be apparent from the following specification taken in connection wtih the accompanying drawings. It will be understood that many changes will be made in the details of the construction, arrangement of parts, without departing from the spirit of the invention as set forth in the accompanying claims. I therefore do not wish to be limited to the exact details of construction, arrangement of parts shown and described as the preferred forms have been shown by way of illustration only.

Referring to the drawings:

Fig. 1 is a side view partially in section, showing the apparatus embodying the invention;

Fig. 2 is a fragmentary top plan view of the apparatus shown in Fig. 1;

Fig. 3 is a sectional view taken on line 3-3 of Fig. 1 looking in the direction of the arrows;

Fig. 4 is a sectional view on an enlarged scale and on line 4-4 of Fig. 1 looking in the direction of the arrows;

Fig. 5 is a sectional view taken online 55-of Fig. 4 looking in the direction of the arrows;

Fig. 6 is a sectional view taken on line 6-6 of Fig. 4 looking in the direction of the arrows;

Fig. '1 is a perspective view of one of the plate members shown in Fig. 1; i

Fig. 8 is a side view of a modified form of the crucible;

Fig-9 is a top plan view of in Fig. 8.

In the past it has been customary in apparatus, such as that set forth in the present application, to employ a crucible comprising a platinum strip or trough or a crucible comprising strands or coils of tungsten wire.

The platinum crucible obviously was very expensive and where used in evaporation of materials requiring temperatures near the melting point of platinum, such as magnesium fluoride, also was short lived. The tungsten crucible was very brittle after being heated to a high temperature in vacuum and susceptible to breaking during the necessary cleaning and handling of the crucible.

It i therefore one of the objects of the present invention to provide a new and improved crucible for supporting the material to be vaporized which will be simple and economical to manufacture and also more eflicient and durable in use than the types employed in the past.-

Also, in the past it has been customary to employ an electrode which projected through the base of the vacuum chamber and was sealed therein with wax or similar substances. In such constructions where the material to be vaporized the crucible shown requires a very high temperature the heat frequently softens the waxor other sealing substances thereby allowing air to leak into the chambers interfering with the vacuum in the vacuum chamber. It is therefore another object of the present invention to provide a new and improved electrode which has cooling means for cooling said electrode during the use of the apparatus, which prevents the heating and softening of the sealing material, thereby obviating the possibility of loss of vacuum in the vacuum chamher through air leaking into the chamber around the electrode and also providing a more reliable structure.

Also, in the past, where the material to be vaporized was a highly transparent substance, there has been encountered considerable difliculty because the heat rays would pass through the transparent material and were not absorbed thereby and consequently a considerable amount or the available heat was not utilized and escaped and it was therefore diificult to vaporize such transparentmaterial. It is therefore an object of this invention to provide a new and improved means and method for preventing such loss of heat where the material to be evaporated is transparent, and for absorbing the radiated heat and consequently facilitate the vaporization of such transparent materials and also for increasing the volume density of the radiant energy.

Referring more particularly to the drawings wherein similar referring characters designate corresponding parts throughout similar views, the device embodying the invention comprises a base I on which is supported the bell jar, or the like, 2 to form the vacuum chamber.

Extending through the base IV is the pipe '3, which is connected to the vacuum pump to exhaust the air from the chamber and form a vacuum in the vacuum chamber. This pipe 3 is also employed toallow chamber after the vaporization process is completed.

Also extending through said base I are the electrodes 4. While two such electrodes have been shown it will be understood that any desired number thereof may be employed. Each of these electrodes 4 comprises a post portion 5 and a base or lower part 6. The said lower part 5 has a threaded portion adjacent the upper end thereof adapted to threadedly engage the threaded bore adjacent the lower end of the portion 5 to hold the parts in assembled relation.

. The lower part 8 is also adapted to extend through an opening in the base I and has a shoulder portion 1 on which is placed an insulation disk 8 of Pyrex glas, or other suitable material.

Surrounding the portion of the lower part 8 which extends through the opening in the base I is a glasstube 9. This glass tube 9 provides insulation for said electrode and also provides means of centering the upwardly extending portion of said part 5.

On the upper surface or the base I is an insulation disk Ill similar to the Pyrex disk 8 and on this disk III is a metal washer I I.

The insulation disk 8 is secured to the shoulder I on the part 8 by means of wax or other suitable material, and then a layer of wax or an adhesive comprising an alkyd resin made by the reaction of glycerol and ethylene glycol with phthalic anhydride known commercially as Glyptal I2 is placed between the upper surface of said in tion disk 8 and the lower surface of said base I.

Adjacent the lower end of the part 8 is secured the electrical contact I3 by means of nut member l4. a

The lower part 6 oi'said electrode is provided with the internal boreor opening I5 which extends through the portion of said part 6 which extends through the base I. In this opening or bore I5 is the water cooling is adapted to enter said cooling jet I6 through the hose, or the like I'I,-and said water is adapted to be then exhausted from said opening I5 through the opening I8 in the lower side of part 5 and through the hose I9. Because said electrodes are water cooled the crucible may be pushed to much higher temperatures than previously possible.

The upper portion of said part 6 is provided with the groove or slot 20 which allows the air to be readily exhausted from the pocket in the air to enter the vacuum Jet iii. The water base I, containing the insulator 3, during the forming of the vacuum in the vacuum chamber. The lower portion of the upper .part 5 is provided with the cylindrical opening 2| and communi-* eating slots 22 which allow the air to be exhausted from the connection between the parts 5 and 5.

Adjacent the upper end of part 5 is secured the clamp member 23 by means of the nut, or the like 24. This clamp member 23 has a portion 25 adapted to receive the end 26 of the electrode support 21 and said end 28 is then secured or clamped in said opening 25 by means of the clamp screw 28.

Each of the electrodes 4 shown in Figs. 1 and 2 are formed in a manner similar to that described above. The crucible clamp members 21 are each formed with the slot members 48 adapted to receive the end 29 of the platinum contact portion of the crucible. The members 21 are also each provided with a slot 30 adapted to allow the insertion of a socket wrench member to allow the j spreading of the parts to allow the insertion of said member 29 in the said opening 48.

The crucible member 3| has the clamping portion 32 of said platinum contact secured thereto i by a bolt or the like, 33 and the contact member 32 has a reduced extension 29 adapted to enter the slot 48 as described above.

I have found that by making the crucibles 3i of a carbon, or carbonaceous type material such as carbon, graphite, silicon carbide, the silicon carbon type of-material known commercially as Globar, or thelike, that the said crucibles are much more durable and also have better heat characteristics and that this form of crucible is considerably more economical than any of the prior art types. These crucibles 3i are made in well form and may be formed from a block of carbon or other suitable material by any suitable manner and where the carborundum type of material is used may be molded, such crucible comprises a body portion 3| and two integral extension portions 46 adapted to be clampingly engaged by the platinum contacts 32. Instead of said platinum contacts 32 carbon connectors may be employed. The crucible 3i is heated by the passage of the current through the crucible. Carbon and silicon carbide become better conductors of the electrical current as their temperature increases and thus permit a great amount of power to be drawn therethrough. If desired an induction coil may be placed around the crucible instead of passing the current directly therethrough. The form shown in Fig. 1 has the integral cross portion 35 for added strength. The crucible is provided with opposed slots 34 to cause better current distribution throughout the crucible. Without these slots 34 a considerable portion of the electrical current is short circuited across the top of the crucible.

In the form shown in Fig. l, embodying the connecting portion 35 the resistance of said connecting portion 35 ismade sufliciently high by controlling the cross section of said connecting portion 35, that the amount of current short circuited through said connecting portion 35 is low.

The form of crucible shown in Figs.8 and 9 does not have this upper connecting portion 35 and this form is also provided with the opposed slots 34 in the sides thereof.

In the vacuum' chamber is provided a pair of upright membbrs 36 adapted to support an object 31 which is retained in the annular support 38 by means of the clamp screws or the like 39, and the lower surface 40 of said object 31, which is adapted to be coated by the material vaporized transparent material and are not absorbed thereby, I have found that by mixing said transparent material with an opaque material, that said opaque material will absorb the radiated heat and warm the particles of the transparent mate-. rial by thermo-conductivity and reradiation.

For example, where the material to be evaporated is quartz, beryl, albeit, cryolite or calcium fluoride, the opaque material to be mixed therewith may be graphite, silicon carbon type of material known commercially as Globar or the silicon carbide material known commercially as Carborundum.

Each of the members 21 are provided with the opposed marginal slots ll and 42 and these slots are adapted to slidingly engage the edges 41 of the slotted portion of shield members 44 and 45.

It will be seen from Fig. 2 that the said shield members 44 and II havevtheir outer portions adapted to overlap but it is essential that these outer portions do not contact so as not to conduct the current which would otherwise pass through the crucible.

The purpose of the shield members H and I5 is to prevent heat and said vaporized material from reaching the lower edge and sides of the bell jar 2 and also keeps the vaporized material from reaching the electrodes and thereby obviates the necessity of cleaning the electrodes or sides of the bell jar. Also heat is prevented from reaching the bell jar, which is liable to crack or break if too hot.

These shields l4 and I! are preferably made of a material of a relatively high melting point, such as copper, steel. or the like, so that the shields themselves will not break and these shields also tend to deflect heat back toward the crucible, which would otherwise be lost.

From the above it will be seen that I have provided a simple, eillcient and economical means for obtaining all or the objects and advantages or the invention.

Having described the invention, I claim:

1. In a device of the character described an integral unitary crucible structure of carbonaceous material and embodying main supporting means in the form of tongue-like members disposed substantially in alignment with each other and protruding outwardly of the opposed sides of an integral cup-like portion constituting the main crucible portion or the device depending below the main supporting portions with substantially parallel side wall portions terminating in a closed end constituting the base of the crucible, said tongue-like members being of the same material as the cup-like portion to provide resistance to assist in heating said cup-like portion, said side wall portion having substantially diametrically opposed longitudinal slots therein disposed in adirection substantially normal to the line or the main support means with said slots terminating within the body of the crucible both above and below and being so arranged as to direct the current flow through said crucible more directly to the closed end of the crucible with th thickness areas of the support means and main crucible portion being controlled to provide suflicient supporting strength and to provide an amount or resistance sufficient to generate the heat desired in the crucible, and a, contact member secured to the free end of each of said tongue-like members and extending around said free end and clamped thereto.

2. In a device 01, the character described an integral unitary crucible structure of carbonaceous material and embodying main supporting means in the form of tongue-like members disposed substantially in alignment with each other and protruding outwardly of the opposed sides of an integral cup-like portion constituting the main crucible portion of the device depending below the main supporting portions with substantially parallel side wall portions terminating in a closed end constituting "the base of the crucible, said tongue-like members being of the same material as the cup-like portion to provide resistance to assist in heating said cup-like portion, said side wall portions having substantially diametrically opposed longitudinal slots therein disposed in a direction substantially normal to the line of the main support means with said slots terminating adjacent the closed end of the crucible and being so arranged as to direct the current flow through said crucible more directly to the closed end of the crucible with the thickness areas of the support means and main crucible portion being controlled to provide suflicient supporting strength and to provide an amount of resistance sufllcient to generate the heat desired in the crucible, and

a contact member secured to the free end of each of said tongue-like members and extending around said free end and clamped thereto.

3. In a device of the character described an integral unitary crucible structure of carbonaceous material and embodying main supporting means in the form of tongue-like members disposed substantially in alignment with each other and protruding outwardly of the opposed sides of an integral cup-like portion constituting the main crucible portion or the device depending below the main supporting portions with substantially parallel side wall portions terminating in a closed end constituting the base of the crucible, said tongue-like members being of the same material as the cup-like portion to provide resistance to assist in heating said cup-like portion, said side wall portions having substantially diametrically opposed longitudinal slots therein disposed in a direction substantially normal to the line of the main support means with said slots terminating within the body of the crucible both above and below and being so arranged as to direct the current flow through said crucible more directly to the closed end of the crucible with the thickness areas or the support means and main crucible portion being controlled to provide suflicient supporting strength and to provide an amount of resistance suflicient to generate the heat desired in the crucible.

HAROLD OSI'ERBERG. 

